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Strength training: Isometric training at a range of joint angles versus dynamic training

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Strength training with isometric contractions produces large but highly angle-specific adaptations. To contrast the contractile mode of isometric versus dynamic training, but diminish the strong angle specificity effect, we compared the strength gains produced by isometric training at four joint angles with conventional dynamic training. Thirty-three recreationally active healthy males aged 18 - 30 years completed 9 weeks of strength training of the quadriceps muscle group three times per week. An intra-individual design was adopted: one leg performed purely isometric training at each of four joint angles (isometrically trained leg); the other leg performed conventional dynamic training, lifting and lowering (dynamically trained leg). Both legs trained at similar relative loads for the same duration. The quadriceps strength of each leg was measured isometrically (at four angles) and isokinetically (at three velocities) pre and post training. After 9 weeks of training, the increase in isokinetic strength was similar in both legs (pooled data from three velocities: dynamically trained leg, 10.7%; isometrically trained leg, 10.5%). Isometric strength increases were significantly greater for the isometrically trained leg (pooled data from four angles: dynamically trained leg, 13.1%; isometrically trained leg, 18.0%). This may have been due to the greater absolute torque involved with isometric training or a residual angle specificity effect despite the isometric training being divided over four angles.
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Strength training: Isometric training at a range of joint angles versus
dynamic training
JONATHAN P. FOLLAND
1
, KATE HAWKER
2
, BEN LEACH
2
, TOM LITTLE
2
,&
DAVID A. JONES
2
1
School of Sport and Exercise Sciences, Loughborough University, Loughborough, and
2
School of Sport and Exercise Sciences,
University of Birmingham, Birmingham, UK
(Accepted 9 October 2004)
Abstract
Strength training with isometric contractions produces large but highly angle-specific adaptations. To contrast the contractile
mode of isometric versus dynamic training, but diminish the strong angle specificity effect, we compared the strength gains
produced by isometric training at four joint angles with conventional dynamic training. Thirty-three recreationally active
healthy males aged 18 30 years completed 9 weeks of strength training of the quadriceps muscle group three times per
week. An intra-individual design was adopted: one leg performed purely isometric training at each of four joint angles
(isometrically trained leg); the other leg performed conventional dynamic training, lifting and lowering (dynamically trained
leg). Both legs trained at similar relative loads for the same duration. The quadriceps strength of each leg was measured
isometrically (at four angles) and isokinetically (at three velocities) pre and post training. After 9 weeks of training, the
increase in isokinetic strength was similar in both legs (pooled data from three velocities: dynamically trained leg, 10.7%;
isometrically trained leg, 10.5%). Isometric strength increases were significantly greater for the isometrically trained leg
(pooled data from four angles: dynamically trained leg, 13.1%; isometrically trained leg, 18.0%). This may have been due to
the greater absolute torque involved with isometric training or a residual angle specificity effect despite the isometric training
being divided over four angles.
Keywords: Muscle strength, isometric, dynamic, isokinetic, resistance training
Introduction
The most effective means of increasing strength by
high resistance training remains unknown, despite
the obvious importance of this knowledge for
athletic training and rehabilitation. We have re-
cently examined the influence of fatigue in
resistance training (Folland, Irish, Roberts, Tarr,
& Jones, 2002) and the effect of a bout of damaging
eccentric work at the onset of a training programme
(Folland, Chong, Copeman, & Jones, 2001), but
these variables were not found to significantly
influence strength gains.
Studies that have employed isometric contractions
have often reported large and rapid increases in
strength [40% in 8 week s (Young, McDonagh, &
Davies, 1985); 25 54% in 5 weeks (Thepaut-
Mathieu, Hoecks, & Maton, 1988); 30% in 5 weeks
(Lindh, 1979); 27% in 6 weeks (Weir, Housh, Weir,
& Johnson, 1995)], which could suggest that this
type of training is more effective than conventional
dynamic training. A limitation of isometric training is
that it produces highly length-specific adaptations
with considerable strengt h increases at the training
angle, but with little transfer to other muscle lengths
(Kitai & Sale, 1989; Lindh, 1979; Thepaut-Mathieu
et al., 1988; Weir et al., 1995). In contrast, dynamic
training results in smaller strength increases through-
out the range of the training movement (Graves,
Pollock, Jones, Colvin, & Leggett, 1989).
Although there has been considerable attention to
different types of muscle contractions in resistance
training, few researchers have compared isometri c
and dynamic contractions. Duchateau and Hainaut
(1984) compared maximum isometric contractions
(10 6 5 s duration) with rapid dynamic contractions
(100 at 30 40% maximum isometric force). They
found clear evidence for training specificity effects,
with maximum isometric training increasing force
production at high loads, and rapid dynamic
Correspondence: J. P. Folland, School of Sport and Exercise Sciences, Loughborough University, Loughborough LE11 3TU, UK.
E-mail: j.p.folland@lboro.ac.uk
Journal of Sports Sciences, August 2005; 23(8): 817 824
ISSN 0264-0414 print/ISSN 1466-447X online ª 2005 Taylor & Francis Group Ltd
DOI: 10.1080/02640410400021783
contractions increasing velocity with low loads.
However, the dissimilar level and duration of loading
make direct comparison of the two types of contrac-
tions impossible.
Jones and Rutherford (1987) used similar high
relative loads to compare isometric, concentric and
eccentric contractions. They found significantly
greater increases in isometric strength (measured at
the isometric training angle) after isometric training
(more than twofold) compared with concentric or
eccentric contractions. Given the documented large
and highly angle-specific adap tations to isometric
training detailed above, this finding is not surprising.
However, Jones and Rutherford also found evidence
for a greater magnitude and duration of muscle
activation during isometric work that may have
accounted for the large isometric strength gains with
this type of training.
In terms of dynamic/isokine tic strength measures,
we are unaware of any studies that have contrasted
isometric and dynamic training at similar relative
loads, perhaps because of the highly ang le-specific
effects that might be expected. Furthermore, no
research to date has contrasted the mode of
contraction (isometric versus dynamic) indepen-
dently from the length specificity adaptation.
Training isometrically at a range of angles might be
more effective than dynamic training, but without
the concentrated angle specificity associated with
isometric training at just one angle. Furthermore,
this approach facilitates a genuine comparison of
dynamic and isometric strength changes following
these two types of contractions.
Kanehisa and Miyashita (1983a) had participants
train isometrically at a range of angles for 8 weeks,
but unfortunately they did not employ a comparison
group that undertook conventional dynamic training.
In the present study, therefore , isometric training at
four different muscle lengths was compared with
conventional dynamic training (lifting and lowering),
using similar relative loads, and assessed by both
isokinetic and isometric strength measures.
Methods
Study desig n
The large individual variation in the response to
strength training (Carey Smith & Rutherford, 1995;
Haakinen, Komi, & Tesch, 1981) makes the
comparison of strength training protocols between
groups of individuals difficult. In contrast, intra-
individual comparisons, where opposite limbs are
trained using different methods, should highlight the
experimental variable. However, crossover effects
that are typically ascribed to neurological adaptations
may confound this type of intra-individual design
(Moritani & deVries, 1979). To minimize the
influence of possible crossover effects, young
healthy, physically active individu als who might have
less scope for changes in learning and coordination
were recruited. Furthermore, to evaluate the capacity
for neurological adaptation, the ability of the
participants to activate the quadriceps muscle was
assessed before training by the twitch interpolation
technique.
Participants
Thirty-three healthy male volunteers (age 21.5 + 2.1
years; body mass 76.5 + 8.6 kg; height 1.81 +
0.06 m; mean + s) completed 9 weeks of knee
extensor strength training. The participants were
recreationally active with no history of knee or thigh
injury, and had not undertaken any leg strength
training during the previous 6 months. They were
recruited from among the staff and students at the
University of Birmingham and gave their informe d
consent to participate. All participants were in-
structed to maintain their habitual level of activity
throughout the study period. The study was
approved by the local ethics committee.
Training
The training consisted of three sessions per week
(Monday, Wednesday and Friday) for 9 weeks and
every training session was supervised. The partici-
pants trained the quadriceps femoris muscle group
unilaterally. One leg of each participants was
randomly assigned to dynamic training, while the
other leg performed only isometric training. The
order of the training (i.e. isometric or dynamic)
within each training session was randomized. The
training load for both protocols was set at 75% of the
respective maximum lift or force for that training
mode, and the maximum was re-assessed on a
weekly basis.
Isometric training
A standard variable resistance leg extension machine
(Cybex VR2) was adapted for isometric work. A
strain gauge was placed in the tension strap and, after
amplification and digitization, the signal was dis-
played on a computer screen in front of the
participant. This allowed force to be measured with
the training apparatus and provided visual feedback
for each contraction. The participants completed
four sets of 10 repetitions of 2 s duration, with one
set being completed at each of four angles of knee
flexion: 0.87, 1.22, 1.57 and 1.92 rad (508,708,908
and 1108). There was 2 s res t between contractions
and 2 min rest between each set. During each
818 J. P. Folland et al.
training session, the sets (angles) were completed in
a different random order.
Dynamic training
Weights were lifted and lowered for four sets of 10
repetitions with a variable resistance leg extension
machine (Cybex, VR2). The participants were
instructed to take 1 s to lift and 1 s to lower each
repetition, through a range of 2.09 to 0.52 rad (1208
to 308 ), equating to *1.57 rad × s
71
, with a short
pause between lifts and 2 min rest between sets.
The variation in loading throughout the range of
motion with the training machine was also assessed.
Using a hand-h eld digital force transducer (Penny
and Giles, Transducers, Christchurch, UK) placed
perpendicular to the lever arm, the force required to
hold a constant load (10 kg) stationary at different
knee flexion angles (0.87, 1.22, 1.57 and 1.92 rad)
was recorded.
Strength testing
Maximum quadriceps strength of each leg was
assessed pre and post training. Pre-training strength
was measured on three occasions, each 1 week apart.
Post-training strength was measured twice, 3 and 5
days after the last training session. The average
values from the pre- and post-training measurements
were compared to evaluate the gains in strength.
Three different types of strength measurements were
made on each test occasion, which lasted approxi-
mately 40 min. There wa s 15 min rest between the
dynamometer measurements (angle torque and
isokinetic) and isometric strength at 1.57 rad.
Two sets of measurements were made using a
Cybex Norm isokinetic dynamometer (Lumex Inc.,
Ronkokama, NY, USA). The axis of the knee joint
was aligned with the centre of rotation of the
dynamometer arm, and the lower leg was strapped
to the lever arm at the ankle. The participants were
restrained at the waist, shoulders and the distal part
of the thigh, and the backrest was set at 1.74 rad
(1008) from the horizontal base of the seat.
Angle torque relationship
Isometric strength was al so measured at four angles
of knee flexion [0.87, 1.22, 1.57, and 1.92 rad (508,
708,908 and 1108)] using the dynamometer. The
angles were selected in a random order for each
participant and the order was maintained on
successive test occasions . The participants attempted
two maximal voluntary contractions of 3 s duration
at each angle, with 20 s between each contraction
and at least 30 s rest between each angle. During
each maximal voluntary contraction, the participants
received direct visual feedback of the force signal as
well as verbal encouragement.
Isokinetic strength
Knee extension strength was measured at three
velocities, 0.79, 2.62 and 5.24 rad × s
71
(45, 150
and 3008 × s
71
). The participants performed three
practice trials, before three maximal efforts were
recorded at each velocity. There was 30 s rest
between each velocity and the highe st peak torque
from the three trials was recorded.
Muscle activation and isometric strength at 1.57 rad
Measurements of isometric strength at 1.57 rad (908)
were duplicated with a conventional isometric
strength testing chair (Parker, Round, Sacco, &
Jones, 1990). This system affords measurement of
muscle activation as well as being highly reliable
(over the three baseline tests the coefficient of
variation was 3.5% versus 6.9% for the Cybex
dynamometer at the same angle).
Force was measured using a calibrated U-shaped
aluminium strain gauge (Jones & Park er, 1989) with
a linear response up to 1000 N. The participants
performed three maximal voluntary contracti ons of
the leg extensors with at least 30 s between each.
During each maximal voluntary contraction, the
participants received direct visual feedback of the
force signal as well as verbal encouragement.
On one of the pre-testing occasions, electrically
stimulated twitches were superimposed on three
maximal voluntary contractions to estimate the level
of quadriceps activation (Rutherford, Jones, & New-
ham, 1986). Two conducting rubb er electrodes
(*100 cm
2
), with a coating of conducting gel, were
applied proximally and distally to the anterior surface
of the thigh. A CED-1401 (Cambridge Electronic
Design Ltd, UK) triggered the electrical stimuli
(pulse width 50 ms, up to 200 V; Digitimer DS7,
UK) at a frequency of 1.25 Hz and twitch magnitude
was manipulated by changing the current (range 28
50 mA). The size of the twitches during the
voluntary contractions was compared with that at
rest before the contraction to calculate the level of
muscle activation.
Statistical analyses
The data from both dynamometers were expressed
as absolute and relative changes in strength. A three-
way repeated-measures analysis of variance (ANO-
VA, SPSS v11) was performed on the absolute
isometric (time 6 angle 6 training) and absolute
isokinetic (time 6 velocity 6 training) data pro-
duced with the Cybex dynamometer. Re lative values
Isometric versus dynamic strength training 819
from this dynamometer were compared with a two-
way ANOVA for isometric (angle 6 training) and
isokinetic measurements (velocity 6 training). In
each case, Mauchly’s test of sphericity was used to
determine whether the assumption of sphericity was
violated by the data. Where this did occur, the Huyn-
Feldt correction was appli ed. When differences were
found by ANOVA, Tukey’s HSD test was used as a
post-hoc test to ascertain whe re the difference lay.
The data recorded from the conventional strength
chair were evaluated for significance differences
between the training protocols using paired Stu-
dent’s t-tests. The results are expressed as the
mean + standard error of the mean unless stated
otherwise and statistical significance was set at P
5 0.05.
Results
Angle torque relationship
The angle torque relationships of the isometrically
trained and dynamically trained legs were very
similar at the start of the study (Figure 1a). Strength
training, irrespective of type, significantly increased
the isometric strength of the participants at a range of
angles (F
1,32
= 115.9, P 5 0.01). The improvement
in absolute isometric strength was significantly
affected by the type of training, with greater
improvements associated with isometric training
(F
1,32
= 9.0, P 5 0.01). Relati ve gains in isometric
strength were also greater for the isometrically
trained than the dynamically trained leg
(F
1,32
= 7.2, P 5 0.01) (Figure 1b). The percentage
gains in isometric strength varied significantly
depending on the measurement angle (F
3,96
= 11.3,
P 5 0.01), with post-hoc analysis revealing gains at
1.57 rad to be greater than at 0.87 and 1.92 rad (P
5 0.01) and gains at 1.22 rad to be greater than at
1.92 rad (P 5 0.01).
The normalized angle force relationship for the
training machine, specifically the force required to
hold a constant load stationary at different angles of
knee flexion (equivalent to isometric force), dis-
played only a small variation throughout the range of
movement (5 10% variation) (Figure 2). In contrast,
the isometric angle torque relationship demon-
strated the ability of the quadriceps muscle to vary
by 42% throughout the same range (Figure 1a).
Isokinetic strength
Prior to training, isokinetic strength of the isome-
trically and dynamically trained legs was very similar
at the three measured velocities of 0.78 rad × s
71
(241.7 + 6.9 vs. 240.2 + 6.3 Nm resp ectively),
trained leg, 240.2 + 6.3 N × m), 2.62 rad × s
71
(isometrically trained leg, 175.1 + 4.5 N × m; dyna-
mically trained leg, 173.7 + 4.6 N × m) and 5.24
rad × s
71
(isometrically trained leg, 117.8 +
Figure 1. (a) The angle torque relationship, before (open
symbols) and after (closed symbols) isometric (triangles) and
dynamic (circles) training. (b) Percentage increase in isometric
strength at each angle after isometric (shaded bars) and dynamic
(open bars) training (mean + s
x
).
Figure 2. The normalized force required to hold a constant load
stationary at different positions throughout the range of movement
with the Cybex VR2 leg extension machine. Force was normalized
to peak force at 1.22 rad.
820 J. P. Folland et al.
2.62 rad × s
71
(175.1 + 4.5 vs. 173.7 + 4.6 Nm) and
5.24 rad × s
71
(117.8 + 3.1 vs. 116.3 + 3.3 Nm).
Resistance training significantly increased absolute
isokinetic strength at this range of velocities, irre-
spective of the type of training undertaken
(F
1,32
= 70.6, P 5 0.01). The improvements in
absolute isokinetic strength with training were not
affected by the type of training (F
1,32
= 0.02,
P = 0.99). Neither was there an interactive effect of
the type of training on the absolute isokinetic
strength at particular velocities (F
2,64
= 1.96,
P = 0.16).
The type of training did not significantly influence
the relative increases in isokinetic strength per se
(F
1,31
= 0.05, P = 0.83) (Fig ure 3), but did interact
significantly with the gains in isokinetic strength at
different velocities (F
2,62
= 3.6, P = 0.03). However,
post-hoc tests revealed no significant differen ce
between isometric and dynamic training at any
specific velocity.
The relative improvements in isokinetic strength
were significantly influenced by the measurement
velocity (F
2,62
= 5.6, P 5 0.01), and post-hoc analy-
sis revealed greater strength gains at 0.79 rad × s
71
than at 5.24 rad × s
71
, irrespective of the type of
training (P 5 0.05).
Muscle activation and isometric strength at 1.57 rad
During the baseline measurements, the participants
were able to achieve 97.2 + 2.1% (mean + s) of full
activation during maximum isometric contracti ons,
as measu red by the twitch interpolation technique.
Before training, the isometrically and dynamically
trained legs were very similar (647.8 + 17.3 N and
652.8 + 17.7 N. respectively). Both types of training
elicited significant increases in absolute strength (P
5 0.001). There was a significantly greater increase
in strength for the isometrically trained leg than the
dynamically trained leg (15.2 + 1.3% and
11.5 + 1.0%, respectively; P 5 0.001).
Discussion
Both types of resistance training resulted in sign ifi-
cant improvements in isometric and isokinetic
strength. Isometric training at four joint angles did
not result in the highly angle-specific adaptations that
have been reported for isometric training at just one
position (Kitai & Sale, 1989; Lindh, 1979; Thepaut-
Mathieu et al., 1988; Weir et al., 1995). However,
training isometrically produced significantly greater
gains in isometric strength across a range of angles
(assessed with two dynamometers) than training
dynamically. In contrast, both types of training
resulted in similar gains in isokinetic (dynamic)
strength.
The current study was a first attempt to make a
direct compa rison between isometric and dynamic
training contractions, while attempting to negate the
confounding factors of differences in relative loading
(magnitude and duration), and the angle specificity
effect of training isometrically at just one angle. The
experiment was designed so that both training
protocols had an equal duration of tension at the
same relative load. However, there are some issues in
the control of these parameters that could have
influenced the results.
First, even a small discrepancy in the duration of
loading may have an accumulative effect upon
strength gains, as noted by Jones and Rutherford
(1987). Although every training session of each
participant was strictly supervised, during dynamic
training there can be a natural tendency to lift and
lower the weight at a rate of greater than 2 s per lift.
The authors are confide nt that for voluntary training
the duration was matched as closely as possible.
Second, there are a number of aspects to be
considered when comparing the loading of the two
protocols. The intention of equal relative load ing for
the two protocols is clearly complicated when one
considers that the dynamic training involved lifting
(concentric) and lowering (eccentric) phases that
have diverse force capabilities. In the current study,
the intention was to match the relative loading for the
lifting (concentric) phase of the dynamic training
with the isometric training. As maximum isometric
strength is greater than concentric strength, this
matched relative loading accepted a discrepancy in
the absolute level of loading. The dynamic training
involved an average velocity of 1.57 rad × s
71
and the
load was set relative to 1-RM, which was presumably
determined by concentric lifting strength. Force
velocity data from similar subjects (Folland et al.,
2002) demonstrated peak concentric torque at 1.57
rad × s
71
was ~75% of peak isometric torque at the
Figure 3. Percentage increase in isokinetic peak torque at three
angular velocities after isometric (shaded bars) and dynamic
training (open bars) (mean + s
x
).
Isometric versus dynamic strength training 821
same angle (*758 of knee flexion). Therefore, this
discrepancy in absolute loading (i.e. 33% greater
for the isometrically trained than the dynamically
trained leg) was accepted from the onset of the
study to contrast equal relative loading. As there
has been little work comparing these different types
of contractions, it is unclear whether it is absolute
or relative loading that is the critical parameter in
the training response, and in the current study
which would pr ovide the more valid comparison.
An alternative methodology would be to attempt to
match absolute torque in the two training proto-
cols. This approach would clearly negate matched
relative loading and might necessitate sub-optimal
isometric loading in order to balance absolute
torques.
Furthermore, due to the mechanics of the exercise
machine used for the dynamic training, the actual
dynamic training load seems certain to have been
lower than intended for much of the range of
movement. In the current study, we found that a
modern well-en gineered resistance training machine
(Cybex, VR2), with a var iable cam, did not
adequately match the angle torque relationship of
the quadriceps muscle of the participants. It is our
belief that this is commonly the case even with
modern resistance training apparatus. The angle
force relationship for the training machine was very
flat ( 5 10% variation) (Figure 2) in comparison
with the muscle’s ability (Figure 1a), whi ch varied
substantially (42%) throughout the same range of
movement. The contrast of these two curves suggests
that the greatest relative loading will be at the
periphery of the range of m otion particularly at
long muscle lengths where the muscle is at its
weakest. It is therefore not surprising that the
commonly observed ‘‘sticking point’’ limiting a lift
is at the beginning of the movement (long muscle
lengths, 5 1.92 rad), especially when one considers
that the inertia of the load must also be overcome at
this point. If the maximum lift (1-RM) was limited
by strength at this point, then the prescribed relative
training load (75% 1-RM) is likely to only have
provided the desired loading at this point, with less
than the prescribed training load during the remain-
der of the movement. For example, as the movement
progressed to an angle of 1.22 rad (708), in contrast
to 1.92 rad (1108), there is a disproportionate
increase in the muscle’s ability compared with the
small additional torque required at this angle. It can
be estimated that at 1.22 rad the same lift would
equate to only 58% of maximum concentric torque,
rather than the prescribed 75%. This implies that the
dynamic training load may have varied between 58
and 75% of isometric training torque, according to
the angle under consideration, and implies the
isometric training load was 33 75% greater than
the dynamic training load. This clearly represents a
substantial discrepancy.
In an attempt to compare isometric and dynamic
loading independent of angle specificity, we tried to
match the relative loading of the two protocols. In
retrospect, due primarily to the surprisingly flat
nature of the angle force relationship of the training
machine, this was not achieved, and this accentuated
the difference in absolute torque of the two training
protocols. Future work would benefit from a more
uniform relative loading throughout the range of
motion for the dynamic training so as to accurately
equate the relative loading.
The overall findings from the two dynamometers
used for isometric measurement were similar (Cybex
Norm and conventional strength chair: significantly
greater isometric strength gains with isometric
training), but in terms of the magnitude of the gains
in isometric strength at 1.57 rad, there was a clear
discrepancy between them (conventional strength
chair: dynamically trained vs. isometrically trained
leg, 11.5% vs. 15.2 %; Cybex Norm: dynamically
trained vs. isometrically trained leg, 20.0% vs.
21.9%). It is not clear why there was such a
difference in the magnitude of recorded strength
gains (1.4 1.7-fold greater for the Cybex dynam-
ometer). It may be partially attributed to the lower
reliability of the Cybex (coefficient of variation: 6.9%
vs. 3.5%). Most commercial dynamometers are
designed primaril y for rehabilitation and their pad-
ding reduces the reproducibility of positioning the
participant and causes greater compliance within the
measurement system. Additionally in the current
study, only two maximal voluntary contractions were
attempted at each angle with the Cybex, as opposed
to three with the conventional strength chair.
However, it is difficult to see how any difference in
reliability might affect the magnitude of the strength
changes.
To remove the concentrated angle-specific effects
of isometric training at just one angle, four distinct
yet contiguous isometric angles were selected (0.87,
1.22, 1.57 and 1.92 rad). This more diverse
isometric training employed in the present study
did not produce strength gains that were as large as
those reported for isometric training at just one angle
[e.g. 35% after 12 weeks of training (Jones &
Rutherford, 1987)]. This was not surprising con-
sidering that only a quarter of the training stimulus in
the present study was specific to any given angle.
The significantly greater isometric strength gains
with isometric training, compared with dynamic
training, could be attributed to different factors.
One possibility is a residual angle specificity effect.
Although the current isometric training was divided
over four angles, considering the potent angle
specificity effect observed with isometric training at
822 J. P. Folland et al.
just one angle, there may still have been a residual
angle specificity effect. In particular, greater gains in
isometric strength at the training angles, but smaller
gains at other angles. In contrast, the dynamic
training involved a larger range of motion (dynamic
vs. isometric: 0.52 2.09 vs. 0.87 1.92 rad) and a
more diffuse training stimulus. Unfortunately, the
current study did no t include isometric strength
measurement at angles between or outside of the
training angles, but this would be strongly advised in
future research.
The greater gains in isometric strength with
isometric training could be due to a contractile
mode specificity effect, with isometric training
producing neurophysiological adaptations specific
to isometric contractions. Although there is strong
evidence for a contractile mode spe cificity effect
when contrasting concentric and eccentric training
(Hortobagyi et al., 1996), independent of an angle
specificity effect, the authors are not awar e of any
evidence for a contractile mode specificity discre-
pancy between isometric and concentric strength.
Finally, and perhaps most likely, the higher
absolute torques associated with isometric training
(estimated as 33 75% higher) may account for the
greater isometric strength gains observed. This
appears to be a substantial difference, particularly
as the level of loading is considered critical to the
training response (Atha, 1981; McDonagh & Davies,
1984), and therefore seems a probable explanation
for the greater isometric strength gains with isometric
training.
The significantly greater strength gains at the mid-
range angles (1.57 and 1.22 rad), irrespective of the
type of training, was an unexpected finding. In terms
of isometric training, it could be hypothesized that
there might be transfer of strength gains at one
position to adjacent angles/positions. After 6 weeks
of isometric training at one angle, Weir et al. (1995)
found significant increases in strength up to 0.52 rad
(308) from the training angle. If this were the case in
the present study, the mid-range angles would
exhibit the greatest strength gains as they would
receive tran sfer effects from both adjacent shorter
and longer muscle lengths. The greater gains in
isometric strength at mid-range angles with dynamic
training is contrary to our previous findings (Folland
et al ., 2002) as well as the proposed rationale that the
highest relative loading occ urred at long muscle
lengths. Our earlier stu dy employed a similar
dynamic training machine, but found significant
increases in isometric strength only at the longer
muscle lengths. The reason for these contradictory
findings is unclear.
Overall, the increases in isokinetic strength were
fairly similar for isometric and dynamic resistance
training. There was no effect of the different types of
training upon isokine tic strength gains per se,orat
any specific velocity. However, from Figure 3 there
appears to be a steeper drop-off in strength gains at
higher velocities for the isometrically trained than the
dynamically trained leg, and the pattern of isokinetic
strength gains across the three velocities was sig-
nificantly different according to the type of training.
This is in agreement with the literature, which
indicates a degree of velocity specificity in strength
training (Caiozzo, Perrine, & Edgerton, 1981; Coyle
et al., 1981; Kanehisa & Miyashita, 1983b; Moffroid
& Whipple, 1970). The fact that only half of the
dynamic training involved concentric activity may
also have confounded the chances of finding a
velocity-specific effect in the current study. While it
is dynamic lifting and lowering that is the widely
practised form of resistance training, a comparison of
purely concentric and isometric work would provide
a more interesting neurophysiological comparison.
Isokinetic strength gains were significantly greater
at 0.79 rad × s
71
than at 5.24 rad × s
71
, irrespective of
the type of training. The training velocities for both
types of training (isometric, 0; dynamic, 1.57
rad × s
71
) were closest to the slowest isokinetic test
velocity of 0.79 rad × s
71
, and most distinct from the
fastest test velocity of 5.24 rad × s
71
. This provides
further evidence for a velocity specificity effect.
In conclusion, training isometrically at four angles
produced significantly greater gains in isometric
strength across a range of angles (assessed with two
dynamometers), but similar gains in isokinetic
(dynamic) strength in comparison to dynamic train-
ing. The greater isometric strength gains could be
due to a residual angle specific ity effect or, perhaps
more likely, the greater absolute torque involved with
isometric training.
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824 J. P. Folland et al.
... Burke et al. [8] reported that performing maximal IST resulted in significantly increased maximum hip extensor force production in as short as 5 days. In addition, Folland et al. [13] reported that IST resulted in similar magnitude in the improvement of isokinetic knee extension after performing IST (10 × 2 s × 75% maximal contraction knee extension at four knee angles) when compared to variable resistance strength training. In contrast, Lee et al. [20] reported that the magnitude of improvement in isokinetic leg extension strength after performing IST (undergoing 10 × 1 s × 75% maximal contraction knee extension at four knee angles) was only half of that after performing isokinetic strength training. ...
... In contrast, Lee et al. [20] reported that the magnitude of improvement in isokinetic leg extension strength after performing IST (undergoing 10 × 1 s × 75% maximal contraction knee extension at four knee angles) was only half of that after performing isokinetic strength training. Although participants in both studies performed 10 repetitions of isometric contraction per session, the duration of the contraction in Folland et al. [13] 's protocol was double of that in Lee et al. [20] (2 s vs. 1 s). The sustained contraction protocol (i.e. ...
... The sustained contraction protocol (i.e. maintaining isometric contraction for > 1 s) used by Folland et al. [13] could have resulted in relatively greater strength gain than the non-sustain contraction protocol by Lee et al. [20], as was reported in other studies [3,30]. Nevertheless, the findings from the aforementioned studies indicated that IST is also an effective method for increasing muscular strength. ...
Article
Full-text available
PurposeIsometric strength training (IST) with rapid non-sustained contraction (RIST) is effective in improving the ability to generate force rapidly. However, the neuromuscular adaptation of IST with sustained contraction (SIST) and RIST is not known. Therefore, the aim of the study was to compare the neuromuscular adaptations of RIST with SIST.Methods Thirty-three national floorball players (23.9 ± 3.1 years old; 1.69 ± 0.08 m; 64.6 ± 11.1 kg) were recruited for this study. Pre- and post-test included countermovement jump (CMJ), 30-m sprint (TT30), isometric squat at 90° (ISqT90) and 120° (ISqT120) knee angles. They were randomly assigned to either control (Con) (n = 9), RIST (n = 12) or SIST (n = 12) group and performed 12 sessions of intervention training. All groups performed the same sets of exercises, but RIST and SIST had to perform ISqT with and without sustained contraction, respectively.ResultsTime × group effect for CMJ height (P = 0.01, ƞ 2p = 0.25), peak force (PF) (P = 0.03, ƞ 2p = 0.22) and rate of force development (RFD) (P = 0.02, ƞ 2p = 0.22) obtained from ISqT120 were noted. A main effect for time was observed in CMJ height, PF obtained from ISqT90 and ISqT120, and RFD obtained from ISqT90 (P < 0.01, 0.27 < ƞ 2p < 0.57). There was greater improvement in TT30 (P = 0.043, d = 3.00), ISqT90 PF (P = 0.034, d = 3.12), ISqT120 PF (P = 0.003, d = 4.54) and ISqT120 RFD (P = 0.033, d = 1.36) in the SIST than the Con group.ConclusionSIST was more effective in improving strength and dynamic performance as compared to RIST, making it a viable training method to enhance dynamic performances.
... (Bentley et al., 2010;Tanimoto & Ishii, 2006) Additionally, close to the CON and the ECC final angles, training protocols with longer MAD generate greater torque than protocols with short MAD. (Bentley et al., 2010;Tanimoto & Ishii, 2006) Given that 1RM test performance (e.g., knee extension machine) is limited by a "sticking region" at the beginning of the movement (i.e., CON muscle action), (Folland et al., 2005) it is possible to expect that protocols with shorter MAD could be more effective for maximum dynamic strength increases due to high torque generated at the initial angles of the CON muscle action. ...
... (Brown & Weir, 2001) An alternative is the use of maximal voluntary isometric contraction (MVIC) tests at varying joint angles. (Alegre et al., 2014;Folland et al., 2005;Ullrich & Brueggemann, 2008) Thus, considering that there is an anglespecificity in maximum isometric strength performance (Noorkoiv et al., 2014;Thepaut-Mathieu et al., 1988) and that MAD influences the instantaneous torque along with the ROM. (Tanimoto & Ishii, 2006) Therefore, it is possible to hypothesise that larger MVIC gains would occur at initial angles of the ROM for faster training protocols. ...
... The sample size was calculated by the software G. Power (version 3.1.7). An effect size value of 0.45 was obtained through the relative change in performance in the MVIC test at the 90° angle (the angle that showed the least relative difference in comparing two experimental groups) using data from Folland et al. (2005) Participants were informed about the study objectives, procedures, and risks and freely signed an informed consent form. The local ethics committee approved this study, which complied with the Declaration of Helsinki. ...
Article
The present study investigated the effect of 10-week matched (range of motion, volume, intensity, rest, and repetition duration) training protocols with varying muscle action duration (MAD) on maximal voluntary isometric contraction (MVIC) test at eight different knee angles and one-repetition maximum (1RM) test after in seated knee extensor machine. Forty women were allocated into one control and three training groups with varying MAD: 5C1E (5s concentric action [CON] and 1s eccentric action [ECC]), 3C3E (3s CON and 3s ECC), and 1C5E (1s CON and 5s ECC). All training groups (5C1E, 3C3E, and 1C5E) showed a greater relative response in 1RM performance than the control group (0.1 ± 3.5%, p ≤ 0.05). The 1C5E group presented greater relative increases in the 1RM performance (22.1 ± 11.6%) compared to 5C1E (13.6 ± 9.2%; p ≤ 0.05) and 3C3E (14.1 ± 5.5%, p ≤ 0.05) groups. The training groups increased the MVIC performance more than the control group (p ≤ 0.05), although there were no significant differences between the training groups. This study demonstrated that isoinertial resistance training protocols with shorter CON MAD showed greater maximum dynamic strength performance response than matched training protocols with other MAD configurations. However, the configuration of MAD did not induce angle-specificity to increase the maximum isometric strength.
... During periods where athletes are required to participate in competitions frequently, one might consider the use of isometric exercises to replace some dynamic exercises in a training program for athletes to reduce the risk of elevated levels of fatigue. Because IST has been shown to be effective in increasing maximum strength at the joint angle that was adopted during training (15,37) and has been shown to increase anglespecific strength more than dynamic strength training (13,20), athletes may adopt IST when they want to improve their force production specifically at the most biomechanically disadvantaged joint position of a particular movement. For example, athletes could replace half the volume of dynamic back squat with isometric squat (ISqt) performed at the joint position that corresponds to the sticking point of back squat so as to enhance their force generation capability at that joint position. ...
Article
Lum, D, Joseph, R, Ong, KY, Tang, JM, and Suchomel, TJ. Comparing the effects of long-term vs. periodic inclusion of isometric strength training on strength and dynamic performances. J Strength Cond Res XX(X): 000-000, 2022-This study compared the effects of including isometric strength training (IST) for consecutive 24 weeks (CIST) against a periodic inclusion (PIST) of this mode of training on strength and dynamic performances. Twenty-four floorball athletes (age: 23 6 2.7 years, stature: 1.74 6 2.08 m, and body mass: 72.7 6 14.4 kg) were randomly assigned to the control (CON), CIST, or PIST group. Athletes completed 20-m sprint, countermovement jump (CMJ), and isometric midthigh pull (IMTP) during pre-test and were tested on weeks 6, 12, 18, and 24. All groups performed a similar strength training program twice per week. However, 2 sets of squats were replaced with isometric squat in CIST for all 24 weeks but only on weeks 1-6 and 13-18 for PIST. A significant main effect for time was observed for 5-, 10-, and 20-m sprint time, CMJ height, peak force, peak power, time to takeoff , modified reactive strength index, IMTP peak force, relative peak force, and force at 200 milliseconds (p 5 ,0.001-0.037). Isometric strength training for 24 consecutive weeks resulted in greater improvement in 5-m sprint time than CON at week 24 (p 5 0.024, g 5 1.17). Both CIST and PIST resulted in greater improvements in 10-m sprint time than CON at various time points (p 5 0.007-0.038 and 0.038, g 5 1.07-1.44 and 1.18, respectively). Isometric strength training for 24 consecutive weeks and PIST resulted in greater improvements in 20-m sprint time than CON at week 6 (p 5 0.007 and 0.025, g 5 1.65 and 1.40, respectively). The results showed that the inclusion of IST resulted in greater improvements in sprint performance than CON but no significant difference in all measured variables with PIST.
... During periods where athletes are required to participate in competitions frequently, one might consider the use of isometric exercises to replace some dynamic exercises in a training program for athletes to reduce the risk of elevated levels of fatigue. Because IST has been shown to be effective in increasing maximum strength at the joint angle that was adopted during training (15,37) and has been shown to increase anglespecific strength more than dynamic strength training (13,20), athletes may adopt IST when they want to improve their force production specifically at the most biomechanically disadvantaged joint position of a particular movement. For example, athletes could replace half the volume of dynamic back squat with isometric squat (ISqt) performed at the joint position that corresponds to the sticking point of back squat so as to enhance their force generation capability at that joint position. ...
Article
Lum, D, Joseph, R, Ong, KY, Tang, JM, and Suchomel, TJ. Comparing the effects of long-term vs. periodic inclusion of isometric strength training on strength and dynamic performances. J Strength Cond Res XX(X): 000-000, 2022-This study compared the effects of including isometric strength training (IST) for consecutive 24 weeks (CIST) against a periodic inclusion (PIST) of this mode of training on strength and dynamic performances. Twenty-four floorball athletes (age: 23 ± 2.7 years, stature: 1.74 ± 2.08 m, and body mass: 72.7 ± 14.4 kg) were randomly assigned to the control (CON), CIST, or PIST group. Athletes completed 20-m sprint, countermovement jump (CMJ), and isometric midthigh pull (IMTP) during pre-test and were tested on weeks 6, 12, 18, and 24. All groups performed a similar strength training program twice per week. However, 2 sets of squats were replaced with isometric squat in CIST for all 24 weeks but only on weeks 1-6 and 13-18 for PIST. A significant main effect for time was observed for 5-, 10-, and 20-m sprint time, CMJ height, peak force, peak power, time to take-off, modified reactive strength index, IMTP peak force, relative peak force, and force at 200 milliseconds (p = <0.001-0.037). Isometric strength training for 24 consecutive weeks resulted in greater improvement in 5-m sprint time than CON at week 24 (p = 0.024, g = 1.17). Both CIST and PIST resulted in greater improvements in 10-m sprint time than CON at various time points (p = 0.007-0.038 and 0.038, g = 1.07-1.44 and 1.18, respectively). Isometric strength training for 24 consecutive weeks and PIST resulted in greater improvements in 20-m sprint time than CON at week 6 (p = 0.007 and 0.025, g = 1.65 and 1.40, respectively). The results showed that the inclusion of IST resulted in greater improvements in sprint performance than CON but no significant difference in all measured variables with PIST.
... Our review clearly detailed (Outcomes section 2.2) that "Isometric training was excluded as this type of contraction is characterized by the application of force at a single point of the ROM and not along its length". This aspect, in addition to a wealth of evidence that the type of contraction significantly influences the adaptations produced (eg, Folland et al. 6 ) makes it difficult to make a direct comparison between both meta-analysis studies. ...
... Conversely, some studies carried out in tennis have not found any relationship between the work of the internal rotation of the shoulder and the speed of the serve in a force test using isokinetic dynamometers (Cohen et al., 1994;Pugh et al., 2003;Signorile et al., 2005). In any case, carrying out training programs related to isometric strength can be associated with significant improvements in actions of a dynamic nature (Folland et al., 2005) and, therefore, can be considered a good option for beach volleyball athletes. ...
Article
Full-text available
The objective of this study was to analyze the relationship between isometric force produced in different joints and its effects on the power kick serve speed in beach volleyball as a predictive aspect to improve sports performance. Seven athletes competing at national and international levels (mean ± standard deviation; age: 21.6 ± 3.20 years; body height: 1.87 ± 0.08 cm; body mass 80.18 ± 7.11 kg) were evaluated using maximum isometric force contractions (i.e., spinal and knee extension, grip by a hand dynamometer (handgrip), internal shoulder rotation, shoulder flexion, elbow flexion and extension, and wrist flexion). Speed of the ball was recorded with a pistol radar and force was measured with a strain gauge. Results showed a relationship between isometric force developed in the internal rotation of the shoulder and speed of the ball (r = 0.76*; p < 0.05). In the remaining isometric exercises, positive low to moderate correlations were found in the spine and knee extension (r = 0.56; p = 0.200) and elbow flexion (r = 0.41; p = 0.375). On the other hand, the remaining isometric exercises obtained weak or non-significant correlations. Force developed in the internal rotation of the shoulder highly correlated with the speed of the power kick, explaining, together with the elbow flexion and the extension of the knee and back, much of the variability of the power kick of beach volleyball athletes.
... In fact, it was previously reported that isometric peak force did not change after undergoing a period of PLYO [36]. The effect of ISO on improving isometric strength is well evident in the literature, and is attributed to improved motor unit activation, firing rate and synchronisation, muscle hypertrophy and tendon stiffness [1,19,20,37]. This increased in ability to produce greater force in the lower limb could be a reason for the improved CMJ height as it was previously reported that individuals were able to jump higher by improving their muscular strength via strength training [36]. ...
Article
Full-text available
The purpose of the study was to compare the change in dynamic and isometric force-time characteristics after plyometric (PLYO) or isometric strength training (ISO). Twenty-two endurance runners (age = 37 ± 6 years,stature = 1.71 ± 0.05 m, body mass = 62.7 ± 8.6 kg, weekly mileage = 47.3 ± 10.8 km) performed a countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) test during pre- and post-tests. They were then randomly assigned to either PLYO or ISO group and completed 12 sessions of intervention over six weeks. The PLYO included drop jump, single leg bounding and split jump, and the ISO included IMTP and isometric ankle plantar flexion. Significant and large time x group interactions were observed for CMJ countermovement depth (P = 0.037, ƞ²p = 0.21) and IMTP and relative peak force (PF) (P = 0.030, ƞ² p = 0.22). Significant and large main effects for time were observed in CMJ height, peak power, propulsive phase duration, countermovement depth, reactive strength index modified, IMTP PF and relative PF (P < 0.05, 0.20 ≤ ƞ²p ≤ 0.65). Effect for time showed small improvement in CMJ height for both PLYO (P < 0.001, d = 0.48) and ISO (P = 0.009, d = 0.47), small improvement in CMJ PP in PLYO (P = 0.020, d = 0.21), large increase in countermovement depth (P = 0.004, d = 1.02) and IMTP relative PF (P < 0.001, d = 0.87), and moderate increase in propulsive phase duration (P = 0.038, d = 0.65) and IMTP PF (P < 0.001, d = 0.55) in ISO. There were large differences between groups for percentage change in countermovement depth (P = 0.003, d = 0.96) and IMTP relative PF (P = 0.047, d = 0.90). In conclusion, both PLYO and ISO improved CMJ jump height via different mechanisms, while only ISO resulted in improved IMTP PF and relative PF.
Article
The use of instrumental diagnosis methods is a way to form an individual strategy of rehabilitation treatment and effectiveness monitoring. However, there is a lack of methods for objective assessment of the muscle groups’ functional state in both patients with dorsopathy and healthy individuals, as well as incorrect use of existing diagnostic tools due to the lack of the regulatory framework. The subjects had no complaints on low back pain, and there was no history of pain episodes associated with spinal pathology. All the volunteers were comparable in height and weight before being included in the study. The study was conducted in accordance with the terms of the Helsinki Declaration, all subjects signed an informed consent before the start of diagnostic activities. Aim. To determine the normative values of the strength of the flexor muscle group (FM) and extensor muscles (EM) of the lumbosacral spine and to establish the ratio of the obtained results to the automatic hardware norm. Material and methods. The present clinical study included 22 healthy volunteers aged 23 to 61 years (the average age was 38.4±12.8 years), including 14 women (63.6%) and 8 men (36.4%). Results and discussion. The results obtained demonstrate that the real normative indicators for MS and MR in healthy individuals can vary in the range from the hardware norm value calculated automatically by the device to a value of 20% lower. Exceeding this parameter is not a pathological deviation. When assessing the muscle strength, a decrease in this indicator is of physiological and clinical significance, since it reflects the dysfunction of this area and is a predictor of the pain syndrome chronicity. Conclusion. The standard values findings allow us to assess correctly the initial clinical condition and use this instrumental method with biofeedback for patients with degenerative spinal lesion and non-specific pain in the lumbosacral region and patients who have undergone spinal surgery to develop individual rehabilitation programs. As a further prospect for the use of diagnostic systems with biofeedback, it is suggested that the examination plan should include the determination of the ratio of the FM strength to the EM strength, as well as the strength of the muscles involved in the lateral slopes of the trunk.
Thesis
***For a copy of this full text please send a private message on research gate to Tom King.*** _____________________________________________________________________________________ Hip extension is a joint action that contributes to athletic movement during performance in various sports. Within the sport of professional soccer, high intensity efforts encompass an important proportion of athletic movement and optimal hip extensor functioning can be seen as a crucial action for the successful performance of such actions. Perhaps related to the importance placed upon high intensity efforts in soccer, the number of hamstring strain injuries that occur are of major concern to practitioners within the field. As such, great efforts are made to establish methods of managing and mitigating these injuries, one of which being improving hip extension function. Methods of establishing an individual’s maximal hip extension strength capacity are available yet are not void of several clinical and practical limitations. As such, understanding the relationship between the specific ability of hip extension with performance and injury related measures are difficult to investigate. Therefore, it may be of use to investigate the development of new strength assessment methods. _____________________________________________________________________________________ In study 1 (chapter 3) a framework of considerations was outlined that surround various methodological and theoretical concepts believed to influence the subsequent validity, reliability and operational success of hip extension assessment tools in the applied field. These considerations arose from information in previous scientific research and from the research team’s (PhD candidate and supervisors) wealth of experience working in applied professional sport. Throughout the framework of considerations, the assessment tools currently available for hip extension strength were critiqued and a rationale for the development of a new tool was outlined. Further into the chapter the adherence of these considerations was presented throughout the development of a new assessment tool (Hip Extension Bench). Finally, the ultimate section of this chapter then introduced information surrounding practical application of the Hip Extension Bench. _____________________________________________________________________________________ In study 2 (chapter 4) the sensitivity of the Hip Extension Bench was investigated where the research team assessed muscle activity and force changes in response to various hip flexion positions. The investigations were undertaken with a mixed population of elite soccer players (n = 10), competitive sprinters (n = 10) and recreationally active males (n = 5) and consisted of assessment across 6 different hip positions (70, 60, 45, 30, 15 and 0 hip flexion). Results displayed precise and specific changes in individual hip extensor muscle activity and force production under maximal isometric contractions at different hip joint angles. Gluteus maximus muscle peak activity was pronounced at positions of inner range hip flexion (0 and 15 deg) whereas maximum force and biceps femoris long head and semitendinosus peak activity was pronounced at positions of greater hip flexion (60 and 70 deg). These data suggest that the Hip Extension Bench can be manipulated to selectively target specific hip extensor muscles and careful precisions must be adhered to upon assessment setup to confirm standardised conditions. _____________________________________________________________________________________ In study 3 (chapter 5) the test-retest reliability of the Hip Extension Bench under non- fatigued conditions was investigated. A group of 40 elite youth soccer players and 15 competitive sprinters undertook maximal isometric hip extension contractions at two angles (15 and 60 deg) on two occasions with a minimum and maximum of 7 and 14 days between test days. Generally, both cohorts demonstrated good reliability of bilateral and unilateral isometric hip extension strength assessments. The findings also demonstrated the difficulties surrounding data collection in the applied field where several complications may arise that influence the subsequent findings and informed decisions that are made on reflection of the data. _____________________________________________________________________________________ In study 4 (chapter 6) the first implementation of the Hip Extension Bench within research surrounding isometric hip extension strength and sprint-acceleration and jump performance associations was presented. A sample of 10 competitive sprinters completed a minimum of three 40 m sprints on test day 1 and a comprehensive battery of strength and power assessments on test day 2 with a minimum and maximum of 7 and 14 days between each test day. The main findings confirmed that isometric hip extension strength was highly correlated with several force-based variables of sprint-acceleration performance (theoretical maximum force; F0, total force; FT Peak, total force across distances of 2, 20 and 40 m; FT 2, 20 & 40 m, mean horizontal force; FH Mean, horizontal force across distances of 2 and 20 m; FH 2 & 20 m and peak power; Pmax) and jump performance in the horizontal direction (the sum of left and right leg horizontal countermovement jumps; UL HCMJ Sum). These findings provide evidence for the role and importance of hip extension strength, specifically under isometric conditions, in high intensity effort performance. _____________________________________________________________________________________ Overall, these findings suggest that a new assessment tool for isometric hip extension strength has been developed that is suitable for application in the environment of applied professional sport. The findings also confirmed the important of hip extension for high intensity effort performance and in conclusion provide a strong rationale for the implementation of the Hip Extension Bench for future research and application in performance and injury management.
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1 Finland HÄKKINEN K., KOMI P.V. & TESCH P.A. Effect of ccmbined concentric ard eccentric strength training and detraining on force-time, muscle fiber-and metabolic characteristics of leg extensor muscles. Scand. J ,Sports Sci. 3 (2): 50-58, 1981. Prog¡essive strength training of combined concentric and eccentric contractions were performed three times a week for 16 weeks by 14 males {20-30 yrs of age) accustomed to weight training. The training peeriod was iollowed bv 8 weeks of detraining. The training program consisted mainly of dynamic exeicises for the ieg-extensovs with loads of 80 to 120 of one maximum repetition The training caused significant improvements in-maximal force (p < 0.001) and various force-time (p (0.05-4.01) para¡àeters. Du¡ing thg I'ast trarning àionìh tbe inãrease in force was gireatly tri¡nited' and there was ¿ decrease in th,e force-time parameters. The marked improvements in mwcle strength were accompanied by ccnsiderable intemål qdaptatioos ,Ín-ttre tnaCned muscle, as Judged from l¡rcreases (p < 0-001) ,iqr. the fibet ãeas ôt tËe Ïast fi¡¡itch (FT) and slow twitch (ST) fibers. Durlng early conditioning improvement i! the qqgs! jump w,as related to tl.e relãtive hypertrop]ty of tr1l ii¡eis fo <0.01). No sier¡j-Êi,cå,r¡t ct¡anges ,in tJre er¡zyme aittv¡tiês oi mÍoki¡¡ase-a¡¡d creatine kirmse were found as a result of-tra¡rrir}g, but i,ndividt¡al charrges in my-o-kinase activity $/ere related to the relative. hypertrop'hy of FT fibers-(p ç 0.05) and Improvernent i+ the squat jump (p < O.Of)-during early conditiontuag. All the ada,p-iatlo:ns'-incilcating musõle hypertrophy occurred. prtm@lv during the last two training mo¡rths. Decreases (p (0.001) in maxirnal force during the detrairring were accompâ-nied bv a sisrificår¡t rediuction in the fi¡b,er areas of ttle fC tp < 0.01) and ST (p < 0.05) tvpes end by a change in bödy-antliropometry.-A periodiè-and partial usage. of àccentr-ic contráctions,-together with conèentric training' is suggested to be effectiùe in training for-maximal force and äso for force-time eharacteristics. In training of longer durations the specific effects of strength trainlng are-obviot¡s and explaiñable by adaptatlons in the trained muscle. Keg tenns: erìzJûne actlvities, muscle mechanics, muscle metabollsn, muscle streng:th.
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Background High resistance training enhances muscular strength, and recent work has suggested an important role for metabolite accumulation in this process. Objective To investigate the role of fatigue and metabolite accumulation in strength gains by comparing highly fatiguing and non-fatiguing isotonic training protocols. Methods Twenty three healthy adults (18–29 years of age; eight women) were assigned to either a high fatigue protocol (HF: four sets of 10 repetitions with 30 seconds rest between sets) to maximise metabolic stress or a low fatigue protocol (LF: 40 repetitions with 30 seconds between each repetition) to minimise changes. Subjects lifted on average 73% of their 1 repetition maximum through the full range of knee extension with both legs, three times a week. Quadriceps isometric strength of each leg was measured at a knee joint angle of 1.57 rad (90°), and a Cybex 340 isokinetic dynamometer was used to measure the angle-torque and torque-velocity relations of the non-dominant leg. Results At the mid-point of the training, the HF group had 50% greater gains in isometric strength, although this was not significant (4.5 weeks: HF, 13.3 (4.4)%; LF, 8.9 (3.6)%). This rate of increase was not sustained by the HF group, and after nine weeks of training all the strength measurements showed similar improvements for both groups (isometric strength: HF, 18.2 (3.9)%; LF, 14.5 (4.0)%). The strength gains were limited to the longer muscle lengths despite training over the full range of movement. Conclusions Fatigue and metabolite accumulation do not appear to be critical stimuli for strength gain, and resistance training can be effective without the severe discomfort and acute physical effort associated with fatiguing contractions.
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Resistive exercise is employed to increase functional performance. Weight lifting has been the traditional program of resistive exercise to increase muscular force (strength). Ten years ago Hellebrandt found that the amount of work done is not as important as the rate at which it is done. The purpose of this study was to determine the specific effects on muscular endurance and on muscular force of two different training speeds. The two training programs administered to two different groups were slow maximal exercise (low power) and rapid maximal exercise (high power). Speed of exercise was found to be specific for muscular endurance and for force increases at and below the exercise speed.
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This paper is adapted in part from a thesis written for the degree of Master of Arts from New York University, New York, and was supported in part by research grant RT-1 (c6) from the Social and Rehabilitation Services, Department of Health, Education, Welfare, Washington, DC under the designation of New York University as a Rehabilitation and Training Center, and in part from grant FR00291 from the United States Public Health Service. Reprinted from Physical Therapy with the permission of The American Physical Therapy Association: Moffroid and Whipple: Specificity of Speed Exercise. Phys Ther 50:1692-1700, 1970.Resistive exercise is employed to increase functional performance. Weight lifting has been the traditional program of resistive exercise to increase muscular force (strength). Ten years ago Hellebrandt found that the amount of work done is not as important as the rate at which it is done. The purpose of this study was to determine the specific effects on muscular endurance and on muscular force of two different training speeds. The two training programs administered to two different groups were slow maximal exercise (low power) and rapid maximal exercise (high power). Speed of exercise was found to be specific for muscular endurance and for force increases at and below the exercise speed. J Orthop Sports Phys Ther 1990;12(2):72-78.
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